Diet and Behavior

The goal of this study was to evaluate the impact of different time-of-day eating patterns on incidence of lifetime mood disorders. From 2004 to 2006, the study assessed 1,304 subjects on their food and drink intake over 24 hours. Their lifetime mood disorder prevalence was measured at follow-up (5 years later) using the Composite International Diagnostic Interview. Three eating habits were identified: grazing (intake spread across the day); traditional (highest intakes as breakfast, lunch and dinner); and late (either skipped or delayed breakfast with greater consumption in the evening). Compared to the adults in the respective pattern at baseline and follow-up, a higher prevalence of mood disorder was seen in the highest third of the “late” pattern (PR=2.04), and a lower incidence observed in the highest third of those eating in the “traditional” pattern (PR=0.31). It was found that the adults in this cohort population who experienced a mood disorder during the follow-up had a 1.07 higher relative risk of being in a higher “late” pattern score category than those who did not experience a mood disorder. This suggests that having an eating pattern that involves skipping or delaying breakfast may increase one's risk of developing mood disorders.

This 2019 cross-sectional study assessed the relationship between breakfast habits and daily food consumption with well-being and sleep quality in a group of 66 healthy young adults. Lifestyle questionnaires and dietary recalls helped identify daily consumption and eating patterns in the study group, while 7-day actigraphy and sleep diaries tracked sleep quality. Increased breakfast frequency over the week showed significant improvements in perceived waking alertness, and was correlated with lower calorie and fat intake across a day. There was also a positive association found between breakfast frequency with perceived sleep quality and perceived waking mood, although no association was discovered with measured sleep duration, latency, and efficiency. When examining the breakfast groups (determined by whether breakfast is consumed 7 days/week or skipped at least once a week), the more consistently breakfast-eating group reported higher perceived sleep quality, mood, and alertness upon waking compared to those who skipped breakfast (p<0.05). Breakfast consumers took in less energy and carbohydrates per day than those breakfast skippers, although variation between the groups in the sleep outcomes was not reported. Overall, Gwin et al. (2019) suggest that breakfast consumption is associated with mood, sleep health, and eating habits in healthy young adults, although further studies examining the causal role of breakfast over a longer time period should be conducted.

In this review, Fiese (2018) discusses food-related time allocation in several forms, and its relationship with our eating habits. Drawing from previous studies, Fiese states that the amount of time dedicated to cooking and dining can be associated with cardiovascular risk and BMI, and therefore focuses on alternate influences on diet and health, such as perception of time intensity and direct observation of allocation during meals. Those who feel time pressure or strain may be less likely to get involved in healthy food related activities and could be at a higher risk for health outcomes. Fiese recommends a socio-ecological approach to the study of time allocation and dietary habits in the United States, and promotes the exploration of direct observation of time use.

This study investigated whether a messy, chaotic kitchen influences snacking behavior, and explores the possibility that different mindsets can lead to either more or less snacking in female students. One hundred and one undergraduate students experienced one of two conditions in this experiment: 1) a standard kitchen, or 2) a chaotic kitchen. The participant’s mindsets were categorized by asking them to recall a time when they felt particularly in control or particularly out-of-control. They were then handed cookies, crackers, and carrots, and their responses were recorded for analysis. The study found that those with an out-of-control mindset and those placed in the chaotic kitchen consumed more cookies than the in-control mindset subgroup, while the chaotic environment had no impact on carrots or crackers consumption. The untidiness and chaos in the kitchen could make one susceptible to making unhealthy dietary decisions, but the individual's mindset can trigger or buffer against this vulnerability.

This 2020 study aimed to analyze the effects of exposing individuals to stress and cues (food and neutral) on their food consumption, and determine if their responses differed by weight status. The 138 participants were exposed to the cues on 3 separate days (using an individualized script-driven imagery task), before being allowed to eat as many snacks (high and low calorie) as they desired after each cue exposure. While food cues were found to elicit significantly greater hunger than neutral and stress stimuli, no difference in cue-induced hunger between weight statuses were observed. Participants also consumed similar numbers in calories after each cue exposure, although a significantly greater proportion (average 81%) came from high-calorie foods in the obese subjects, compared to 63.5% in those in the normal weight category. Weight status did not influence energy contribution from high-calorie foods following the neutral cue, but after the stress cue in particular, 81.4% of what the obese individuals ate were high-calorie snacks, whereas this percentage was 70.2% for those with normal weight. It appears that food and stress cues induced obese participants to consume more high-calorie snack foods than normal weight individuals.

Hess et al. (2016) begin by mentioning the benefits of defining a snack and distinguishing between meals and snacks, since the labeling of a food as one or the other may affect an individual’s food choice and possibly their satiety after consumption. The purpose of this review was to examine the definition of extra eating events, to understand the rationale for eating at these times, and to discover the commonly decided food choices, in order to suggest dietary interventions for improving these habits. In part 1, the writers discuss how snacking is defined, and how an individual’s motivation to snack and snack choices can be influenced. In part II, they present popular snack choices, overall snacking frequencies, and the demographics (across several countries) of those who snack frequently. The authors also inspect snacking’s relationship with cardiometabolic health markers. This review is concluded by an encouragement to promote nutritious snacks with the goal of preventing nutrient deficiencies.

Nas et al. (2017) tested the hypothesis that the timing of skipping meals may affect risk of obesity and type II diabetes by modulating the circadian regulation of energy balance, glucose metabolism, and postprandial inflammatory responses. In this randomized controlled crossover trial, the 17 subjects underwent the following dietary intervention for 3 days: they began with a breakfast skipping day (BSD), received the conventional 3 meals the following day (control), and ended on a dinner skipping day (DSD). Energy and macronutrient balance was measured in a respiration chamber, while the participants’ blood was monitored for glycaemia and insulin section over 24 hours, as well as inflammatory responses in leukocytes, glucose, and insulin levels after food intake. Energy expenditure over the previous 24 hours was reported to be higher in both skipping days when compared with the 3-meal control group, while fat oxidation was greater only in the group who skipped breakfast. No variation was found in spontaneous physical activity, 24-hour glycemia, nor 24-hour insulin secretion between the 3 intervention days. The differences observed between BSD and DSD were increases in postprandial homeostasis model assessment index (+54%), postprandial blood glucose (+46%) and inflammatory potential of peripheral blood cells post-lunch. This trial demonstrated greater energy expenditure in those who skipped meals, and the connection between skipping breakfast with greater fat oxidation and postprandial insulin levels, suggesting that chronic breakfast skipping could irregulate glucose concentrations and lead to inflammation.

Since consumer acceptance is crucial for the success of personalised nutrition services aimed at preventing diseases, Reinders et al. (2020) tried to relate an individual’s ambivalent feelings and contextual factors to their willingness to use personalized dietary services. The researchers obtained data from 797 participants in the Netherlands through an online survey, and tested and compared different models. The risk-benefit calculus model showed a positive correlation between weighing benefits and privacy risks with intention to use personalized nutrition advice, while ambivalent feelings were linked with weaker intentions. This suggests greater uptake of personalized services when perceived benefits outweigh risks. Additionally, more abvilant feelings were expereinced when eating context was perceived as a barrier to use the services of personalized nutrition. These findings imply that personalized nutrition services may need to address affective concerns and consider an individual’s eating context.

In this 2020, study, researchers conducted a project in an urban environment particularly known for unhealthy snacking, and attempted to encourage people to consume healthier snacks by making these healthy alternatives more accessible. In stages, Schlinkert et al. (2020) identified a hotspot location for unhealthy snacking (by tracking people’s snacking locations and conducting surveys), developed and branded an attractive snack for the consumers that was accepted as both healthy and tasty, and designed the small truck where they would be sold. While selling the snacks from the truck at the unhealthy snacking hotspot, people were asked for their opinions on the snack and its branding. This revealed that the consumers appreciated the snack, the truck and the branding, although the actual sales figures were very low. The common snacking and purchasing habits of the consumers may explain the low sales; based on the data gathered from this project, easing people’s access to healthy snacks may not be sufficient to encourage consumers to choose healthier snack foods. It was proposed that perhaps selling the healthy snacks directly beside popular snack purchase locations may increase attention and recognition.

Bracale et al. (2020) conducted a 14-question survey based on the updated Mediterranean diet pyramid to determine the respondents’ eating behaviors and compliance to the Mediterranean-like dietary pattern since this habit may help prevent certain chronic diseases. While this cross-sectional study targeted subjects over the age of 19, the vast majority of participants (75.6%) were female, 20.7% were in the younger category, and 33.1% had a university degree. Sedentary lifestyle was prevalent in 37.8% of the sample population, including in 29.6% of those aged 20-29 years. Moreover, females and older people especially did not adhere to recommendations included in the Mediterranean diet pyramid. One of the highlights was the discrepancy identified between the responders' perceived and actual behaviour toward their regular consumption of fruits and vegetables. The results emphasize the lack of adherence to the Mediterranean diet recommendations shown by Italian adults.

Timlin et al. (2020) conducted a systematic review to find and qualitatively evaluate trials that implement whole dietary patterns using a Social Cognition Model. The purpose was to thoroughly assess the effectiveness and psychological theory of dietary interventions that encouraged a whole eating pattern. The 9 studies that met the inclusion criteria were then analyzed to find that interventions improved at least one food group in studies reporting on individual food group scores. Overall, based on the Theory Coding Scheme (research tool that determines the extent to which theory was applied to design interventions), it was suggested that studies were not vigorously applying theory to intervention design. We should investigate further to determine the most important behaviour change theory and techniques in dietary interventions.

In this 2014 study, regular chocolate consumers were deprived of chocolate for one week and were provided with pictures of chocolate and high-calorie non-chocolate containing foods before and after this week of abstinence. Blechert et al. (2014), who planned to analyze the impact of food restriction, saw more liking, wanting, and consumption of chocolates, as well as greater feelings of frustration among participants during the intervals between the trials. Considering the findings from the eyeblink startle responses as well, these results indicate that hedonic deprivation (restriction of intake of certain foods without energy deficit) has profound effects on experiential, behavioral and attentional/appetitive response systems. The author also discusses what these findings mean for dieting research and practice, and specifically for eating and weight disorders.

This 2011 review explains the phenomenon that is entrainment by food and specifically by palatable snacks. Escobar et al. (2011) say the signals transmitted by the biological clock, that normally adjusts to the daily light/dark (LD) alternation, can be influenced and overridden by food. There usually exists a correct coordination between the light/dark transition and the food elicited time signals with the circadian system, but this synchronisation within the body becomes disturbed if food is consumed during the regular resting/sleep phase. This review suggests that scheduled feeding may lead to food addiction and that altered eating schedules can alter dietary behavior and result in obesity and abnormal metabolic responses.

This 2015 meta-analysis was designed to measure the impact of induced positive and negative mood on the food consumption of healthy subjects as well as those with eating and weight disorders. Two meta-analyses were conducted on the 33 studies selected (totalling 2491 participants) to compare negative/positive mood with neutral mood. Poor mood was significantly associated with more food intake particularly in restrained and binge eaters, while positive mood was also related with increased consumption in calories across groups. The findings suggest there could be a causal link between negative mood and more food intake which requires further exploration.

Happy eating: The Single Target Implicit Association Test predicts overeating after positive emotions

In this 2016 study, 190 undergraduate women were randomly assigned to either an anger or neutral mood condition, before completing the Food Stroop task (assesses attentional bias), and then given the chance to eat mandarin oranges and/or chocolate candy while the experimenter was not present in the room. The plan was to examine the effect of attentional bias and negative affect on food consumption. The results showed that women high in negative urgency (NU) who experienced emotional arousal were more likely to consume candy and more candy than any other woman participant. Attentional bias was not related to food intake, and was unaffected by emotional arousal or emotional valence (interest/attractiveness). The influence that negative mood has on consumption of palatable foods appears to involve emotional arousal rather than emotional valence, and may be primarily seen in women high in negative urgency.

This 2017 review examined the prevalence of grazing (unstructured, repetitive eating of food in small amounts) in adults with eating disorders and/or obesity in both clinical and community settings. Although grazing has been linked with negative results following bariatric surgery, little is known about about this dietary pattern in eating disorders and in obese individuals who have not undergone surgery. Heriseanu et al. (2017) here found 38 criteria-meeting studies through systematically searching online databases, before conducting a meta-analysis on 32 studies with data on prevalence. The mean pooled prevalence of grazing was found to be 33.2% in obesity before weight loss treatment, 28.16% in obesity at follow-up, and 23.32% in the community. Grazing was also reported in 58.25% of bulimia nervosa cases, 67.77% of people with binge eating disorders, and 34.31% of anorexia nervosa sufferers. It was therefore deduced that grazing is substantially common in obesity and in eating disorders. This review presents inconsistent evidence linking grazing with poorer weight loss treatment outcomes in obesity, lower mood, worsening of eating disorders, and decreased mental health-related quality of life.

Relating goal-directed behaviour to grazing in persons with obesity with and without eating disorder features

In this 2018 meta-analysis, Evers et al. (2018) planned to analyze the impact of emotions on eating in both healthy individuals and patients with eating disorders. The researchers gathered 56 experimental studies on the causal effect of emotions on eating behavior, and performed separate meta-analyses for negative and positive emotions. Also investigated was the degree to which restrained/emotional eating and being overweight/obese moderated the overall impact of emotions on dietary behaviors. The results demonstrated that negative emotions did not affect eating in overweight/obese participants, those with eating disorders and self-assessed emotional eaters, but increased food intake among restrained eaters. Positive emotions on the other hand, saw greater dietary consumption across all groups. Heterogeneity of these studies was found to be high, although these findings appear to indicate restrained eaters’ higher vulnerability to emotion-induced eating.

This 2020 study explored emotional overeating by exposing participants to a personalized emotion induction while showing images of palatable foods, and assessing the effect of emotion condition (negative, neutral) and individual differences (self-reported trait emotional and restrained eating) on outcome variables such as facial expression, brain reactivity, valence (attractiveness) and desire to eat. The results revealed increased attractiveness and appetitive reactions to palatable foods in individuals with higher emotional eating scores in the negative condition, but the opposite effect in those with lower emotional eating scores. A similar pattern was observed for desire to eat ratings among participants who showed greater response to the emotion-inducing technique, indicating a dose-response interaction. Furthermore, increased brain activation was apparent among restrained eaters in the negative condition when viewing images of foods compared to objects. The appetitive reactions seen in emotional eaters backed up emotion regulation theories, while the brain activity towards food compared to objects among restrained eaters support cognitive theories. The authors believe further investigation is necessary, particularly on eating disorders with emotion regulation difficulties.

Feeling bad or feeling good, does emotion affect your consumption of food? A meta-analysis of the experimental evidence

A systematic review of the association between emotions and eating behaviour in normal and overweight adult populations

A humanities-based explanation for the effects of emotional eating and perceived stress on food choice motives during the COVID-19 Pandemic

The effects of negative and positive mood induction on eating behaviour: A meta-analysis of laboratory studies in the healthy population and eating and weight disorders

The aim of this 2018 study was to determine the association between types of emotional eating with psychological and physical health variables. A total of 189 overweight/obese adults enrolled for this study, completed a number of questionnaires and reported their height and weight. More frequent eating in response to depression, anxiety/anger, and boredom were all related to poorer psychological well-being, more eating disorder symptoms, and increased difficulty managing emotions. While eating in response to depression was most closely related to the psychological variables, all 3 of these previously mentioned emotional eating types were associated with specific disordered eating emotions. Positive emotions were not linked with any of the outcome variables. Braden et al. (2018) suggest there may be unique patterns connecting specific types of emotional eating with psychological outcomes.

Is comfort food actually comforting for emotional eaters? A (moderated) mediation analysis

To eat or not to eat: Effects of food availability on reward system activity during food picture viewing

The neurocognitive mechanisms underlying food cravings and snack food consumption. A combined continuous theta burst stimulation (cTBS) and EEG study

According to Emilien & Hollis (2017), we need to fully understand the factors that modulate people’s dietary behaviors not only because food choices are linked with risk of developing certain chronic diseases and some forms of cancer but industrial food production is believed to be unsustainable and greatly contribute to the greenhouse gas emission. There is evidence that a combination of factors such as physiology, environment, psychology, culture, socio-economics and genetics, play a part in influencing eating behavior. These single factors have been identified but the authors believe the interaction between these factors will be helpful in developing new models of eating behavior. This current review portrays how complex eating behavior really is by discussing the impact of several important physiological and environmental factors on meal initiation, meal size (satiation) and inter-meal interval (satiety). A number of limitations that may apply to this area of research is also revealed.

Breakfast consumption in relation to lowered risk of psychological disorders among Iranian adults

In this 2019 study, focus groups and interviews were organised in the United States with 24 adults (aged between 26-77) who either had a body mass index within the healthy range or had overweight/obesity. The aim was to analyze and compare their internal and external cues for overeating. The five external factors influencing the participants’ food consumption were: environmental cues including food availability and variety; standard expectations for dietary intake; food palatability; social pressures to overeat; and perceived social expectations around eating. Overweight/obese individuals regarded these five factors challenging, and found it difficult to find solutions in order to avoid overconsumption. People found it particularly tough dealing with the social pressures and perceived social expectations. Interventions aimed at healthy weight management may target these potential obstacles to weight control identified in this study.

Kenny (2011) states that while humans consume food to keep energy levels balanced for optimal functioning, palatable food is also eaten due to its pleasure-inducing properties, which is what leads to excessive caloric intakes relative to requirements, and significantly contributes to the growing obesity problem in developed countries. Since little is known about the pleasure-related (hedonic) brain systems that affect food intake, compared with the knowledge on homeostatic mechanisms of feeding, this review presents the recent progress made in the understanding of these brain circuitries that control hedonic aspects of eating behaviors. The author also points out that certain brain circuitries stimulated by the uncontrolled intake of palatable foods are similar to those seen to be involved in drugs of abuse. Evidence has emerged suggesting that obesity and drug addiction may share common hedonic mechanisms. Those genetically vulnerable to drug addiction may be at greater risk of developing obesity.